Acid secretion by the boring organ of the burrowing giant clam, Tridacna crocea. (30th June 2018)

• Record Type: Journal Article
• Authors: Hill, Richard W.; Armstrong, Eric J.; Inaba, Kazuo; Morita, Masaya; Tresguerres, Martin; Stillman, Jonathon H.; Roa, Jinae N.; Kwan, Garfield T.
• Is Part Of: Biology letters. Volume 14:Number 6(2018)
• Publication Date: 2018-06-30
• Subjects: bivalve -- pH -- bioerosion -- vacuolar-type H+-ATPase; Biology -- Periodicals; 570.5
• DOI: 10.1098/rsbl.2018.0047
• Languages: English
• ISSNs: 1744-9561

Abstract

Abstract : The giant clam Tridacna crocea, native to Indo-Pacific coral reefs, is noted for its unique ability to bore fully into coral rock and is a major agent of reef bioerosion. However, T. crocea 's mechanism of boring has remained a mystery despite decades of research. By exploiting a new, two-dimensional pH-sensing technology and manipulating clams to press their presumptive boring tissue (the pedal mantle) against pH-sensing foils, we show that this tissue lowers the pH of surfaces it contacts by greater than or equal to 2 pH units below seawater pH day and night. Acid secretion is likely mediated by vacuolar-type H + -ATPase, which we demonstrate (by immunofluorescence) is abundant in the pedal mantle outer epithelium. Our discovery of acid secretion solves this decades-old mystery and reveals that, during bioerosion, T. crocea can liberate reef constituents directly to the soluble phase, rather than producing sediment alone as earlier assumed.